647640840 has 768 divisors, whose sum is σ = 2836684800. Its totient is φ = 116121600.

The previous prime is 647640811. The next prime is 647640869. The reversal of 647640840 is 48046746.

It is an interprime number because it is at equal distance from previous prime (647640811) and next prime (647640869).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 20891625 + ... + 20891655.

It is an arithmetic number, because the mean of its divisors is an integer number (3693600).

Almost surely, 2^647640840 is an apocalyptic number.

647640840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 647640840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1418342400).

647640840 is an abundant number, since it is smaller than the sum of its proper divisors (2189043960).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

647640840 is a wasteful number, since it uses less digits than its factorization.

647640840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106 (or 95 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 39.

The square root of 647640840 is about 25448.7885762761. The cubic root of 647640840 is about 865.1898366021.

The spelling of 647640840 in words is "six hundred forty-seven million, six hundred forty thousand, eight hundred forty".